1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying apparatus, a printer, or a facsimile apparatus, and more particularly to an apparatus in which an upper body is opened from and closed to a lower body.
2. Related Background Art
In an image forming apparatus for executing an image formation by an electrophotographic process, there is known a configuration in which the apparatus is divided into an upper part and a lower part, in order to facilitate a process of removing a sheet jamming at the recording operation or a work of inspection and maintenance. Such configuration is known as a clam shell type in which an upper body can be opened from and closed to a lower body.
In such image forming apparatus, the upper body becomes considerably heavy as it includes for example an image reading apparatus.
The upper body of such considerable weight requires a large operating force for opening and closing. Consequently, in such image forming apparatus, an elastic member such as a gas spring is provided between the upper body and the lower body.
Such elastic member allows to open the upper body automatically or with a small operating force.
However, such gas spring may become weaker in the repulsive force by a deterioration in time, thus becoming unable to provide a necessary opening amount. Also such gas spring requires a cumbersome work for replacement, as it has a very strong elastic power and is fixed on both ends.
Therefore, Japanese Patent Application Laid-Open No. H06-324529 discloses a proposal for the replacement of the gas spring.
In the following a procedure of gas spring replacement will be explained with reference to FIG. 14, also quoting Japanese Patent Application Laid-Open No. H06-324529.
A prior gas spring 1004 has both ends as indicated by 1004a, 1004b in FIG. 14. The upper end 1004a of the gas spring has a C-shaped recess (grooved portion or rotatable portion) in order that it can rotate on a mounting pin 1006a. This portion, merely impinging on a mounting member on the main body, can be detached from the main body by slightly lifting an upper frame member 1006 of the main body or by slightly contracting the gas spring.
At the lower end 1004b of the gas spring, a rod of the gas spring 1004 has a rounded end which is mounted on a recessed support member 1006 in a rotatable manner. Thus the dismounting can be achieved by detaching the upper side of the gas spring and then extracting the gas spring, thus not requiring any tool and within a limited work space.
However, the above-described prior configuration poses following difficulties when the gas spring 1004, supporting the upper frame member 1006 of the main body, is detached from the mounting pin 1006a shown in FIG. 14. The dismounting operation is difficult to execute for the replacing workman (for example service personnel) as he has to hold the gas spring 1004 in one hand and to support the considerably heavy upper frame member 1006 of the main body by another hand.
Also in case the upper frame member 1006 of the main body is left free by mistake, the considerably heavy upper frame member 1006 may close forcibly, and may impair the safety of the workman in replacing work.